r/vmagent: Deploy vmagent

The *vmagent* role installs and configures the scraping and routing
agent used in the Victoria Metrics ecosystem.

roles/vmagent/files/vmagent.service

@@ -0,0 +1,13 @@
+[Unit]
+Description=Victoria Metrics vmagent
+
+[Service]
+Type=exec
+Environment=httpListenAddr=[::1]:8429
+Environment=loggerDisableTimestamps=true
+EnvironmentFile=-/etc/sysconfig/vmagent
+ExecStart=/usr/bin/vmagent -enableTCP6 -envflag.enable
+User=victoriametrics
+
+[Install]
+WantedBy=multi-user.target